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How to Extend Yout USB Using UTP

Introduction: How to Extend Yout USB Using UTP

This is my second Instructables. This time, I'm gonna tell everyone how to extend your USB using UTP. Why do you need to do so? Because the USB extender in shops only around 1,5 meters. It's very short, if you need 50 meters for a USB WiFi antenna on your roof. So I share to you people this technique.

P.S.: I will be making the Instructables of the Indonesia's style of USB WiFi antenna. The picture is below.

There is a lack of research here, and a lot of misunderstanding about cables, ie twisted pair or shielded etc.

To put the record straight, its nothing do do with either of the above, you can have the best cable in the world, even fancy gold plated low resistance stuff, and the chances of getting any appreciable RELIABLE extra distance above the 5 metre limit is virtually zero.

The reason for this is not interference, nor is it voltage drop, but the timing of the signals that USB uses. Two of the cores are for power, +ve and Ground (red and black) the other two, green and white are clock and data (signal). The clock is a chain of pulses thats used to synchronise the data between the device and the PC, the data, well its just that. What happens when you extend a USB cable is to add a delay in the signals, for example, when a USB sevice wants to send data to the PC, it will do so on the start of the clock pulse, and any data it then sends is kept in step with the clock. As you increase the length of the cable, you increase this delay, to such a point where the data ends up completely out of step and meaningless to the other end.

No, USB is differentially encoded; each data line is NRZI encoded data + clock. The D+ is the normal signal and D- is inverted. USB then uses a non-symmetric state to indicate end of packet. I cannot see how timing could be an issue when transmitting digital data over long distances unless one of the UTP pairs are of unequal length. USB does suffer from RF noise due to it's operating frequency, and at lengths also suffers from induced slew due to natural capacitance of the wires. The former can be guarded against with shielded-twisted-pair, the latter can only be avoided by keeping the cables short. High-Speed USB operating at 240 MHz is prone to RF interference at 720 MHz which is used by 3G and 4G cell phones. Full-Speed at 12 MHz or low-speed (750 kHz) would be far more practical at line lengths this long (aka, USB 1.1 if your BIOS supports downgrading or grab an old USB 1.1 hub from eBay).